Gem/Gem Topic of the Month

Each month this section will feature either a topic of interest to gem lovers or one special gemstone with background on the material and its value.

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April, 1998 (Revised, August, 2004)

Rubellite Tourmaline

Rubellite is the name given to dark pink to red tourmalines, especially those with reasonably saturated colors and medium to dark tones. Ruby red stones with little orange or brown overtones are the most highly sought after. GIA has traditionally classified rubellite (along with Emerald) as a Class III gem, meaning that it is almost always included. This is less true in recent years as deposits from certain regions of Africa yield much cleaner rough. Alas, these stones, so often tinged with brown, almost never approach the ruby like color of the best of those from older Brazilian deposits. Russia, Brazil, Madagascar, Nigeria and the US are productive sites for this gem.

Natural pink to red color is created by trace amounts of manganese in the chemical composition. Cat's eye stones are sometimes available. Irradiation, a now common practice, can produce stable red tones in otherwise pale pink stones. As this practice is undetectable all stones must be presumed to be treated even though this may not be the case for an individual stone.

Highly included rubellites are sometimes treated with fillers similar to those used on emeralds. This treatment, however, is detectable by standard methods. All tourmalines make excellent jewelry stones and require no special care.


Value

Due to scarcity and beauty, the most valuable pieces are untreated, clean (eyeclean or better) deep pinkish red to slightly purplish red stones. Those with light pink color are sometimes offered as rubellite, but more properly should be labelled pink tourmaline. Brownish tones decrease value considerably. A custom cut adds value, although the majority of Brazilian pieces are native cut.


Gemological Data

Makeup: a complex borosilicate

Luster: Vitreous

Hardness: 7.5

Crystal structure: Trigonal

Fracture: conchoidal

Density: 3.06

RI: 1.62 - 1.64

Birefringence: .018

All text and images, unless otherwise designated, © 2004 Barbara Smigel


Stones Currently Available:

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Go to: Homepage -- what's new in faceted gems -- what's new in designer cabochons and gem carvings -- gem of the month -- gem of the month archive -- birthstone of the month -- key to all the codes used on the ACS site -- definitions of terms used on the ACS site -- how to order -- about ACS -- about the ACS cutters -- settings for these gems --faceting information -- purchase UltraTec equipment